From 9074b8d943d41b4539c78f1183128e61aee5485c Mon Sep 17 00:00:00 2001
From: Moonchild <moonchild@palemoon.org>
Date: Sun, 15 Oct 2023 00:19:13 +0200
Subject: Issue #2281 - Build LZ4 as C instead of including it as C++.

---
 mfbt/Compression.cpp | 12 ++----------
 mfbt/moz.build       | 13 ++-----------
 mfbt/objs.mozbuild   |  2 ++
 3 files changed, 6 insertions(+), 21 deletions(-)

diff --git a/mfbt/Compression.cpp b/mfbt/Compression.cpp
index 6147d0d611..8dc2ec3d86 100644
--- a/mfbt/Compression.cpp
+++ b/mfbt/Compression.cpp
@@ -11,17 +11,9 @@
 // corecrt_memory.h.
 #include <string>
 
-using namespace mozilla::Compression;
-
-namespace {
-
-extern "C" {
-
-#include "lz4.c"
+#include "lz4.h"
 
-}
-
-}/* anonymous namespace */
+using namespace mozilla::Compression;
 
 /* Our wrappers */
 
diff --git a/mfbt/moz.build b/mfbt/moz.build
index 54b13f21b9..e4b294292d 100644
--- a/mfbt/moz.build
+++ b/mfbt/moz.build
@@ -124,20 +124,11 @@ SOURCES += mfbt_nonunified_src_cppsrcs
 
 DISABLE_STL_WRAPPING = True
 
-# Suppress warnings in third-party LZ4 code.
-# TODO: Remove these suppressions after bug 993267 is fixed.
-
-if CONFIG['GNU_CXX']:
-    SOURCES['/mfbt/Compression.cpp'].flags += ['-Wno-unused-function']
-    CXXFLAGS += ['-Wno-error=shadow']
-
 if CONFIG['CLANG_CXX']:
     # Suppress warnings from third-party V8 Decimal code.
     SOURCES['/mfbt/decimal/Decimal.cpp'].flags += ['-Wno-implicit-fallthrough']
 
-if CONFIG['_MSC_VER']:
-    # Error 4804 is "'>' : unsafe use of type 'bool' in operation"
-    SOURCES['/mfbt/Compression.cpp'].flags += ['-wd4804']
-
 if CONFIG['MOZ_NEEDS_LIBATOMIC']:
     OS_LIBS += ['atomic']
+
+DEFINES['LZ4LIB_VISIBILITY'] = ''
diff --git a/mfbt/objs.mozbuild b/mfbt/objs.mozbuild
index 8aed3d179f..e8fd522d79 100644
--- a/mfbt/objs.mozbuild
+++ b/mfbt/objs.mozbuild
@@ -28,9 +28,11 @@ mfbt_src_cppsrcs = [
 
 # Compression.cpp cannot be built in unified mode because it pulls in Windows system headers.
 # Decimal.cpp doesn't build in unified mode with gcc.
+# We build lz4 in C mode
 mfbt_nonunified_src_lcppsrcs = [
     'Compression.cpp',
     'decimal/Decimal.cpp',
+    'lz4.c',
 ]
 
 mfbt_nonunified_src_cppsrcs = [
-- 
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